In spite of strong plant breeding efforts against plant pathogens, plants continue to be susceptible to pathogenic diseases, including viral, bacterial and fungal organisms. Historically these plant pathogens have had devastating impact on entire nations, with the most extreme example being the Irish potato famine. Even today, many vegetable crops have been subjected to disastrous diseases, such as the recent tomato mosaic virus outbreak that destroyed plants in entire tomato greenhouses. As a result of these diseases, yields of vegetable crops are reduced and consumer prices increase dramatically.
To combat these problems, plants may be treated with chemical compositions in an attempt to provide protection from pests and diseases to promote improvements in yield, growth, and/or productivity. However, there is a continual need to develop new methods to improve the protection of plants from distinct types of pathogens such as fungal, bacterial, and viral diseases.
As evidenced by the $10 billion market for agricultural fungicides, nearly all plants are treated in an effort to control fungal infections. However, bacterial infections and viral infections in plants are much more difficult to contain. Although plant genetics, antibiotics, and insecticides can be tried in this regard, these methods only offer partial solutions to the problem. Therefore, it is highly desirable to provide compositions that offer disease tolerance for plants against one or more of fungal, bacterial, and viral diseases.
Furthermore, providing long-term improvement in plant disease tolerance is also extremely desirable. Methods that reduce the incidence and severity of diseases in plants in a convenient and lasting manner would be extremely advantageous. For instance, treatment of plants prior to shipment and transplantation of the plants to the field would provide a tremendous benefit to the industry.
Accordingly, the present disclosure provides methods of improving disease tolerance of a crop plant by improving and/or inducing long-term disease tolerance of the crop plants against one or more of fungal, bacterial, and viral diseases. The methods provided in the present disclosure have desirable properties and related advantages compared to other methods known in the art. First, the methods of the present disclosure are unexpectedly effective against multiple disease-causing agents such as fungi, bacteria, and viruses. Second, the methods of the present disclosure offer long-term protection against disease-causing agents, so that plants may be treated early in development and have observable disease resistance several weeks after application. Finally, the improvement in plant disease resistance may provide for higher yields of crops and require less pesticide use for growing plants. These combined benefits provide marked improvements over comparable methods known in the art.